竖直矩形窄通道内水沸腾换热的流型研究

Study of the Water Boiling Heat Exchange Flow Pattern in a Vertical Rectangular Narrow Channel

采用可视化方法观测了竖直矩形窄通道内单侧加热水的两相流型,发现主要有孤立气泡流,合并气泡流,搅拌流和环状流4种流型。与多数文献中类似工况的流型图对比,发现流型转变与通道宽深比、流体压力和加热条件有关。与现有的流型转变标准相比,大部分的流型转变界线都不能被很好的预测,因此有必要开发新的理论模型用于预测单面加热的窄通道内水和水蒸汽两相流型的转变标准。

By employing the visualization method,observed was the two-phase pattern of a water flow heated at a single side in a vertical narrow channel.It has been found that there mainly exist four kinds of flow pattern,namely,isolated bubble flow,combined bubble flow,agitation flow and annular flow.Contrasted with the flow pattern charts under the similar operating conditions given in the literatures,it has been discovered that the flow pattern transition has some-thing to do with the width-depth ratio of the channel,fluid pressure and heating condition.Compared with the currently available flow pattern transition criteria,the most transition boundaries of the flow patterns cannot be predicted very well,therefore,it is necessary to develop a new theoretical model for predicting the transition of the water-steam two-phase flow pattern of a flow heated at a single side of a narrow channel.